4.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yury Norov ynorov@caviumnetworks.com
commit 8351760ff5b2042039554b4948ddabaac644a976 upstream.
syzbot is catching stalls at __bitmap_parselist() (https://syzkaller.appspot.com/bug?id=ad7e0351fbc90535558514a71cd3edc11681997...). The trigger is
unsigned long v = 0; bitmap_parselist("7:,", &v, BITS_PER_LONG);
which results in hitting infinite loop at
while (a <= b) { off = min(b - a + 1, used_size); bitmap_set(maskp, a, off); a += group_size; }
due to used_size == group_size == 0.
Link: http://lkml.kernel.org/r/20180404162647.15763-1-ynorov@caviumnetworks.com Fixes: 0a5ce0831d04382a ("lib/bitmap.c: make bitmap_parselist() thread-safe and much faster") Signed-off-by: Yury Norov ynorov@caviumnetworks.com Reported-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reported-by: syzbot syzbot+6887cbb011c8054e8a3d@syzkaller.appspotmail.com Cc: Noam Camus noamca@mellanox.com Cc: Rasmus Villemoes linux@rasmusvillemoes.dk Cc: Matthew Wilcox mawilcox@microsoft.com Cc: Mauro Carvalho Chehab mchehab@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- lib/bitmap.c | 2 +- lib/test_bitmap.c | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-)
--- a/lib/bitmap.c +++ b/lib/bitmap.c @@ -607,7 +607,7 @@ static int __bitmap_parselist(const char /* if no digit is after '-', it's wrong*/ if (at_start && in_range) return -EINVAL; - if (!(a <= b) || !(used_size <= group_size)) + if (!(a <= b) || group_size == 0 || !(used_size <= group_size)) return -EINVAL; if (b >= nmaskbits) return -ERANGE; --- a/lib/test_bitmap.c +++ b/lib/test_bitmap.c @@ -218,6 +218,10 @@ static const struct test_bitmap_parselis {-EINVAL, "-1", NULL, 8, 0}, {-EINVAL, "-0", NULL, 8, 0}, {-EINVAL, "10-1", NULL, 8, 0}, + {-EINVAL, "0-31:", NULL, 8, 0}, + {-EINVAL, "0-31:0", NULL, 8, 0}, + {-EINVAL, "0-31:0/0", NULL, 8, 0}, + {-EINVAL, "0-31:1/0", NULL, 8, 0}, {-EINVAL, "0-31:10/1", NULL, 8, 0}, };